The different members of the growth hormone family of proteins (including the naturally occurring diabetogenic substance) will be characterized in regard to their different activities and physical properties. Radioimmunoassays for distinguishing these different growth hormone forms in the circulation of diabetics are being developed. Their diverse effects on islet cell secretion and metabolism will be determined and correlated with their effects on endothelial cell growth, Factor VIII production and proteolytic activity. The effect of the diabetic state on physical and functional properties of Factor VIII and on Factor VIII-platelet-endothelial cell interaction will be studied. Alterations in the rigidity of platelet membranes in diabetes will be investigated using extrinsic nitroxide stearic acid spin probes I(m,n). Possible causes for such altered rigidity will be explored.